This invention relates to a fan casing, and particularly to a casing for a wall fan having a cover for closing the opening of the casing and a solenoid-operated means to open the cover.
Typically, the casing of a wall fan includes a front opening and a rear opening provided with grilles for passage of the air when the fan operates. Such a wall fan is usually mounted in an opening in a wall of an enclosed space for ventilation. A drawback of the wall fan is that, when the operation of the fan is not needed, such as on rainy days or cold days, the fan casing becomes an undesirable passage in a wall through which undersirable things, such as insects, rats, and cold air can intrude into the enclosed space. Moreover, over a long period of time, exposure of the fan to rain water and bad weather results in reduced service life of the fan.